1. The Field of the Invention
The present invention relates to airbag inflation systems in motor vehicles. More specifically, the invention relates to an airbag diffusion system for diffusing inflation gases exiting a curtain airbag inflator.
2. Technical Background
Inflatable airbags are well accepted for use in motor vehicles and have been credited with preventing numerous deaths and injuries. Some statistics estimate that frontal airbags reduce the fatalities in head-on collisions by 25% among drivers using seat belts and by more than 30% among unbelted drivers. Statistics further suggest that with a combination of seat belt and airbag, serious chest injuries in frontal collisions can be reduced by 65% and serious head injuries by up to 75%. Airbag use presents clear benefits and vehicle owners are frequently willing to pay the added expense for airbags.
A modem airbag apparatus may include an electronic control unit (ECU) and one or more airbag modules. The ECU is usually installed in the middle of an automobile, between the passenger and engine compartments. If the vehicle has a driver airbag only, the ECU may be mounted in the steering wheel. The ECU includes a sensor which continuously monitors the acceleration and deceleration of the vehicle and sends this information to a processor which processes an algorithm to determine if the vehicle is in an accident situation.
When the processor determines that there is an accident situation, the ECU transmits an electrical current to an initiator in the airbag module. The initiator triggers operation of the inflator or gas generator which, in some embodiments, uses a combination of compressed gas and solid fuel. The inflator inflates a textile airbag to impact a passenger and prevent injury to the passenger. In some airbag apparatuses, the airbag may be fully inflated within 50 thousandths of a second and deflated within two tenths of a second.
An airbag cover, also called a trim cover panel, covers a compartment containing the airbag module and may reside on a steering wheel, dashboard, vehicle door, along a vehicle roof rail, vehicle wall, or beneath the dash board. The airbag cover is typically made of a rigid plastic and may be forced open by the pressure from the deploying airbag. In deploying the airbag, it is preferable to retain the airbag cover to prevent the airbag cover from flying loose in the passenger compartment. If the airbag cover freely moves into the passenger compartment, it may injure a passenger.
Airbag apparatuses have been primarily designed for deployment in front of the torso of an occupant between the upper torso of an occupant and the windshield or instrument panel. Conventional airbags, such as driver""s or passenger airbags (hereinafter referenced as the xe2x80x9cprimary airbagxe2x80x9d), protect the occupant""s upper torso and head from colliding with a windshield or instrument panel.
Airbag technology has advanced to include airbag apparatuses which protect occupants during a side impact, or roll-over accident. In these accidents the occupant may be thrown against the windows, doors and side-walls of the vehicle. These airbag apparatuses are known as curtain airbags. Generally, the curtain airbag is attached to a thin long frame member which runs along a side of the roof of the vehicle. Often due to window size and visibility requirements, the curtain airbag apparatus has a long thin shape.
The airbag of a curtain airbag apparatus inflates and descends from the frame member to cover a majority of the area between the occupant and the side of the vehicle interior. The inflated airbag appears much like a curtain covering the vehicle window. The curtain airbag may protect the occupant from impact with a side window, flying shards of glass, and other projectiles. The curtain airbag may also help to keep the occupant inside the vehicle during a roll-over accident.
Generally, the un-inflated curtain airbag is installed in a very limited thin space defined by the roof frame member. Accordingly, the inflator may be a thin, cylindrical member which extends a portion of the length of the curtain airbag. In this manner, the curtain airbag inflator is capable of providing sufficient inflation gas to properly inflate the curtain airbag.
Generally, the inflator is installed within the textile bag of the curtain airbag apparatus. However, doing so generally requires the inflator to include a diffuser. Gas which fills the curtain airbag is generated by the ignition of gas generant within the inflator. Generally, the gas is created from the rapid burning of pyrotechnic materials. The gas (also referred to herein as exhaust gas) escapes exit ports in the inflator at a high velocity and temperature. Due to the limited space, the textile bag is generally stored by folding it up against the inflator. Without a diffuser, the hot gas is concentrated on the textile bag. The concentrated hot gas and the confined space may combine to cause the gas to burn one or more holes in the airbag material, which is generally a nylon or polyester weave. The holes cause the curtain airbag to inflate improperly.
A diffuser disperses the exhaust gas. Dispersing the gas allows the gas to expand and cool. A diffuser may also include a surface which further allows the gas to transfer some of its heat. A diffuser may be used to direct the gas leaving the exit ports. Gas may be directed to cause the textile airbag to inflate in a particular manner. Once the gas passes through a diffuser, the gas is sufficiently cooled and/or not concentrated to prevent burning holes in the textile airbag.
A diffuser may be built as part of the body of the inflator. Generally, doing so adds to the production and design costs of the inflator. Alternatively, separate parts may be secured to the inflator at appropriate points to function as diffusers and to direct the exhaust gas. When a diffuser is incorporated into the body of the inflator, this may require custom fabrication of inflator bodies for different vehicles. Custom fabrication is also expensive.
Accordingly, it would be an advancement in the art to provide an airbag diffusion system which is simple to fabricate. It would be a further advancement to provide an airbag diffusion system which directs the gas using a standardized inflator. Additionally, it would be an advancement in the art to provide an airbag diffusion system which prevents concentrated gas jets and cools the gas exiting the inflator to prevent holes in the airbag material. A further advancement in the art would be to provide a diffusion system and method of fabrication having minimal expense. The present invention provides these advancements in a novel and useful way.
The apparatus of the present invention has been developed in response to the present state of the art, and in particular, in response to the problems and needs in the art that have not yet been fully solved by currently available airbag inflator diffusion systems. Thus, the present invention provides an airbag inflator diffusion system which is simple to fabricate and install, directs gas exiting the inflator, effectively diffuses and cools the gas, and may be fabricated with minimal expense.
In one embodiment, the airbag inflator diffusion system includes an airbag inflator. The inflator includes one or more gas exit ports disposed along its surface. The system also includes a sleeve. The inflator is installed securely within the sleeve. Generally, the sleeve is cylindrical in shape. Alternatively, the sleeve has a cross-section capable of receiving the inflator. The sleeve cross-section may be in a diamond, triangular, or parallelogram shape. The inflator is secured within the sleeve by the tight fit and bias between the sleeve and the inflator. The sleeve may include a lip or flange at each end to aid in securing the inflator within the sleeve. The sleeve includes one or more lobes.
A lobe is a solid rigid material formed as part of the sleeve and positioned such that gas leaving the exit port is impeded by the lobe. The lobe forces the gas to go around the lobe before entering the textile bag. Preferably one lobe is positioned above each exit port of the inflator. Depending on the positions of exit ports in the inflator, the lobes are generally positioned on alternating sides along the length of the sleeve.
In an alternative embodiment, the airbag inflator diffusion system includes a catch. The catch impedes gas flow from both ends of a lobe to the interior of the airbag. The catch serves to keep residue particles of the ignited gas generant from entering the airbag. These residue particles may be very hot and may cause holes in the airbag material. The catch also helps diffuse the exhaust gas. The catch may be a wire or fabric mesh.
The present invention includes a method of manufacturing a curtain airbag inflator diffuser. In one embodiment, a rigid cylindrical tube having a hollow space capable of receiving a curtain airbag inflator is bent. The tube is bent such that the tube obtains an elliptical cross-section and remains capable of receiving and securing the curtain airbag inflator.
Then, one or more sections of the tube are removed to form a lobe and an exhaust passage. The curtain airbag inflator is then inserted into the hollow space. The curtain airbag inflator and/or tube are then adjusted such that exits ports of the curtain airbag inflator aim toward lobes of the tube. A catch may be inserted between the inflator and the lobes such that exhaust gas is thereby impeded from leaving the exhaust passage.
According to an alternative embodiment of the method of manufacturing a curtain airbag inflator diffuser, a plurality of parallel slits are formed perpendicular to the longest edge of a pliable, planar, rectangular plate. The plate is bent on each side of each slit such that a plurality of lobes having triangular cross-sections extend in alternating directions perpendicular to the largest surface of the plate. The bending of the plate forms a sleeve. Next, a curtain airbag inflator is inserted between the plurality of lobes such that the curtain airbag inflator is secured within the sleeve. Additionally, a catch may be inserted between the curtain airbag inflator and the sleeve.
These and other features, and advantages of the present invention will become more fully apparent from the following description and appended claims, or may be learned by the practice of the invention as set forth hereinafter.